The present invention generally relates to the collection and removal of floatable debris and, more particularly, to structure for directing water flow into the inlets of the traps of such debris removing systems.
Trash and debris floating on the surfaces of waterways or along shorelines and beaches is a highly visible form of water pollution, which is receiving attention for its adverse, polluting effect and for its unaesthetic appearance on the surfaces of lakes and other water bodies. One type of system for the collecting and removing of floating debris has consisted of arrays of disposable mesh nets installed in receiving bodies of water in the flow path of a sewer outlet, particularly in applications referred to as xe2x80x9cCombined Sewer Overflowsxe2x80x9d or xe2x80x9cCSOsxe2x80x9d. Such systems are described in Vol. 2, No. 3, of Fresh Creek Technologies, Inc. xe2x80x9cShorelinesxe2x80x9d newsletter. Systems of this type are effective in collecting floatables or trash for removal and are shown in Fresh Creek Technologies, Inc. Netting Trashtrap(trademark) Product Bulletin. Improvements in such devices are described in U.S. Pat. No. 5,562,819, owned by the assignee of the present application, which provides an underground, in-line apparatus for trapping and collecting debris in a sewer or storm flow conduit, a secondary trap which provides continued protection when primary collection traps are full, a system which signals when primary bags or nets are full and servicing is required, and a trapping facility in which bags or nets may be replaced without loss of trapping protection during servicing.
More specifically, the device in the patent referred to above includes an enclosure or chamber with an inlet and an outlet each adapted to be connected to a sewer, storm drain conduit or outflow. A debris removing system is disposed within the chamber between the inlet and the outlet for trapping and collecting water borne debris entering at the inlet and thereby providing for an outflow of substantially debris-free water. The enclosure includes an access opening comprising upper doors or hatches or access hatches in the enclosure sized to allow the debris removing system to be removed and replaced. The debris removing system specifically includes a perforated container having an open end facing the inlet of the chamber. The perforated container includes a netting assembly that traps and collects the trash or floating debris. The container is in the form of a netting assembly having a flexible bag-shaped mesh net attached to a frame. The netting assembly is attached to lifting structure having supports or handles for allowing the frame and net to be lifted out when the net is full of captured debris. In some applications, a bypass weir or screen is provided to normally direct flow from the chamber inlet through the open end of the net while allowing flow to bypass the net and flow to the chamber outlet when the net is full of debris.
Sensing and signaling elements are typically provided for sensing and signaling the passage of solid debris around the net when the net is full of debris and is in need of servicing. The sensing and signaling elements may include mechanical structure which permits passage of water, but is displaced by impingement of solid debris flowing around the nets. Displacement of such mechanical structure signals when the net is full of debris, for example, by actuating a visible flag above ground or by actuating an electrical switch which activates an aboveground indicator or remote indicator. The sensing and signaling may include an optical sensor for detecting the passage of debris around the netting assembly. Upon detection of debris, the optical sensor emits a signal indicating that the trap is full of debris. The signal may also activate an aboveground indicator or a remote indicator.
Multiple trap systems are employed in which the enclosure includes side-by-side trap assemblies. Such systems may be configured such that, upon filling of the first trap, the flow and debris can be diverted over a bypass weir disposed between the inlet ends of the first and second traps so that flow is thereby directed through the second trap and overflow debris is trapped and collected. Closure panels may be provided in a stationary frame structure disposed adjacent the inlet ends of the traps in either the single-trap systems or the multitrap systems to restrain debris from flowing through the chamber during servicing.
Floating systems for the removal of floatables or trash are positioned in a body of water in front of an outfall such as a stream or storm sewer conduit through which water flows into the waterbody. The systems are oriented with the mouths of the disposable nets facing the outfall. The system includes a structure that floats on the surface of the water to hold the nets horizontally in the water. The flow is directed toward the mouths of the nets through a funnel-shaped structure in front of the floating structure. The energy of the flow drives the floatables into the disposable nets where they are captured and can be removed. The number of nets in a given system is chosen to handle the anticipated flow from the outfall under specified conditions and to avoid excessive flow velocities in the individual nets.
Floating systems are installed in waterways that have variable water elevations due to tides or other flow patterns. To prevent floatables from escaping around or under the system, weighted curtains are attached to floating booms attached between the shore headwall, on opposite sides of the outfall, and the front corners of the unit and below the mouths of the nets, with the unit facing the outfall. Under designed flow conditions, these curtains direct the flow from the outfall into the mouth of the disposable nets. The curtains extend or hang vertically from the units and the floating booms to the bottom of the waterbody. The vertical length of the curtains is such that they will reach the water bottom under a specified water elevation such as extreme high tide or the 100-year flood elevation.
Under extreme flow conditions, the energy of the flow can place excessive hydraulic forces on the system. Since design of the system for the worst case flow is impractical, a need exists for a method of providing relief to structurally protect the system.
A primary objective of the present invention is to provide relief to structurally protect the system under extreme flow conditions and under the worst case flow.
According to principles of the present invention, a floating debris collecting system is provided with curtains that direct the flow of water that contains floatables into the traps of the system while functioning as a pressure relief mechanism for the system which avoids placing excessive hydraulic forces on the system under extreme flow conditions.
In one embodiment of the invention, inlet flow confining curtains are provided with patterns of weights to cause the curtain to hang in an optimal manner for preventing floatables from bypassing the traps of the system while allowing extreme water flow at depths that are less likely to carry floatables to find a low flow resistance path around the traps. In particular, curtains are provided that are weighted in a manner that causes them to lift off of the water bottom when the velocity of the water and the pressure on the curtains reach predetermined levels. As the lifting occurs, some of the flow of the water pases under the curtains, thereby providing pressure relief. This is achieved by placing weights in the curtain in a series of nominally horizontal pouches or pockets that are fabricated into the curtain at various distances below the water level that hang down to the bottom of the waterbody under normal conditions. The weights are graduated with the heaviest at the top and the lightest at the bottom. This progressive weighting causes the curtain to lift first at the bottom, thus causing the bypass to occur nearest the water bottom, where floatables are less likely to be present, providing pressure relief while minimizing the floatables that escape as the bypass occurs.
In another embodiment of the invention, curtains are provided having openings or windows formed therein that are covered with a mesh material of approximately the same aperture as the mesh of the nets. These windows allow flow through the windows while containing floatables larger than the size of the openings in the mesh. The positions and size of the windows are determined so as to provide a desired pressure relief while still directing the flow into the disposable nets of the traps.
In a further embodiment of the invention, curtains are provided with the vertical corner that is formed by the junction of the side curtain and the funnel curtain constructed with a triangular-shaped pucker pocket that extends from the lower corner of the floating structure to the bottom of the curtains. This pucker pocket allows the two curtains to lift and open at these corners while still containing the floatables that are more likely borne near the surface of the water.
These and other objectives and advantages of the present invention will be more readily apparent from the following detailed description of the of the preferred embodiments of the invention, in which: